The present disclosure generally relates to a hood assembly for use in an automotive vehicle, wherein the hood assembly includes the use of active materials based mechanisms.
Numerous motor vehicles employ a hingable hood disposed in a region between the passenger compartment and the forward bumper of the motor vehicle, or between the passenger compartment and the rearward bumper of the motor vehicle. The hingable hood provides a mechanism for accessing the underlying engine or storage compartment. The vehicle hood is typically formed of a relatively thin sheet of metal or plastic that is molded to the appropriate contour corresponding to the overall vehicle body design. The exterior of the hood portion, which constitutes the show surface thereof, is typically coated with one or more coats of primer and paint for enhancing both the aesthetic character and the corrosion resistance of the underlying material. Due to the relatively thin nature of the material forming the hood portion, a support structure such as a contoured plate with stamped rib supports typically extends across the underside of the hood portion so as to provide a degree of dimensional stability to the structure.
Aerodynamics, styling, and packaging considerations, among others, have all contributed to the design of the front ends and hood regions of current vehicles. Aerodynamic drag (and fuel economy considerations) in particular has contributed to the hood being in close proximity to the engine or storage compartment. Accordingly, hood deformation such as may occur upon impact of an object onto the hood, and thus the ability of the hood to absorb energy at appropriate force levels before bottoming out against hard objects beneath it, is somewhat limited by the contents of the compartment.
In response, automobile manufacturers have proposed a number of mechanisms that change the orientation of the hood before a deformation event such as the impact event previously described. For example, hood lifters may be activated by impact sensors to increase the space between the hood and the underlying compartment. The hood lifters change the orientation of the hood by raising it (in most mechanisms by raising it at a rear edge while maintaining attachment of a front edge to the vehicle structure, i.e., tilting) above the engine compartment. Upon deformation then, because of the increase in clearance there is an increase in the amount of the energy that can be absorbed by deformation of the sheet metal before bottoming out. One drawback to such hood lifting mechanisms is that they tend to be irreversible (which makes them best suited for use only with crash and not with pre-crash sensors), so that such mechanisms will need to be replaced/repaired even if collision does not in fact occur.
Accordingly, there remains a need in the art for automotive hood components having improved energy absorbing capabilities such as may occur upon deformation of the hood. The means/mechanisms that produce this energy absorbing capabilities are preferably reversible as well.